Rear-Wheel Steering Threshold Control for Stability and Maneuvering
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Solution Overview
Problem
Existing four-wheel steering systems for vehicles either rely on passive mechanical systems with fixed rear wheel angles or modern active systems that always steer rear wheels in the same manner, failing to optimize vehicle performance across varying speed and maneuvering conditions.
Innovation Solution
A method for controlling rear steering wheels using independent actuators, an electronic control unit, and a threshold value to adjust steering angles based on speed and maneuvering conditions, allowing in-phase steering at high speeds for stability and counter-phase steering at low speeds, with differential steering angles applied to outside and inside wheels as needed to compensate for actuator limitations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If passive mechanical systems are used with fixed rear wheel steering angles, then the system structure is simple, but the vehicle cannot adapt to varying speed and maneuvering conditions
Solution Approach 1:
The patent applies dynamics by transitioning from fixed mechanical steering angles to dynamically adjustable steering angles. The electronic control system continuously adjusts rear wheel steering angles based on real-time vehicle speed and maneuvering conditions, enabling the system to adapt to varying operating conditions while maintaining manageable complexity through software-based control.
Solution Approach 2:
The patent changes the steering angle parameter from fixed values to variable values that depend on vehicle speed and maneuvering conditions. The electronic control unit modifies the steering angle parameter dynamically based on sensor inputs, allowing the system to optimize performance across different operating conditions without requiring complex mechanical reconfiguration.
2Stability of the object's composition
If rear wheels are steered in-phase at high speeds to improve stability, then vehicle stability increases, but the steering radius increases and maneuverability decreases
Solution Approach 1:
The patent applies dynamics by switching between in-phase and counter-phase steering modes based on vehicle speed. At high speeds, the system uses in-phase steering to maximize stability, while at low speeds, it transitions to counter-phase steering to minimize steering radius and enhance maneuverability. This dynamic mode switching allows the system to optimize both stability and maneuverability across different operating conditions.
Solution Approach 2:
The patent changes the steering phase parameter (in-phase or counter-phase) based on vehicle speed thresholds. The electronic control unit adjusts the steering angle relationship between front and rear wheels according to real-time speed data, transitioning between different steering modes to optimize both stability at high speeds and maneuverability at low speeds.
3Adaptability or versatility
If modern active systems always steer rear wheels in the same manner, then the control system is simple, but vehicle performance is not optimized across varying conditions
Solution Approach 1:
The patent changes the steering angle parameter dynamically based on vehicle speed and maneuvering conditions. The electronic control unit adjusts rear wheel steering angles in real-time according to sensor inputs, allowing the system to optimize performance across different operating conditions. This parameter-based approach maintains relative system simplicity while achieving advanced adaptability.
Data Source
AI summary
A method to control a road vehicle with rear steering wheels and having, while driving along a curve, the steps of: determining a desired steering angle for the rear wheels; comparing the desired steering angle with a threshold value; applying, while driving along a curve and if the desired steering angle is greater than the threshold value, to both rear wheels a same actual steering angle that is equal to the desired steering angle; and applying, while driving along a curve and if the desired steering angle is smaller than the threshold value, to a rear wheel on the outside of the curve an actual steering angle greater than the desired steering angle and applying to a rear wheel on the inside of the curve a zero actual steering angle.